Am 23.09.21 um 02:58 schrieb Dave Airlie:

On Sat, 18 Sept 2021 at 07:57, Alexandre Bailon abailon@baylibre.com wrote:

...

Some Mediatek SoC provides hardware accelerator for AI / ML. This driver provides the infrastructure to manage memory shared between host CPU and the accelerator, and to submit jobs to the accelerator. The APU itself is managed by remoteproc so this drivers relies on remoteproc to found the APU and get some important data from it. But, the driver is quite generic and it should possible to manage accelerator using another ways. This driver doesn't manage itself the data transmitions. It must be registered by another driver implementing the transmitions.

Signed-off-by: Alexandre Bailon abailon@baylibre.com [SNIP]

...

Please refer to https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.kernel...

here and below in many places.

There's a lot of missing padding/alignment here.

There is also the pahole utility which show you nicely where you need padding for your IOCTL structures.

For example "pahole drivers/gpu/drm/amd/amdgpu/amdgpu.ko -C drm_amdgpu_gem_va" gives you:

struct drm_amdgpu_gem_va {     __u32                      handle;               /*     0     4 */     __u32                      _pad;                 /*     4     4 */     __u32                      operation;            /*     8     4 */     __u32                      flags;                /*    12     4 */     __u64                      va_address;           /*    16     8 */     __u64                      offset_in_bo;         /*    24     8 */     __u64                      map_size;             /*    32     8 */

/* size: 40, cachelines: 1, members: 7 */     /* last cacheline: 40 bytes */ };

And as you can see we have added the _pad field to our IOCTL parameter structure to properly align the 64bit members.

Regards, Christian.

...

I'm trying to find the time to review this stack in full, any writeups on how this is used from userspace would be useful (not just the code repo, but some sort of how do I get at it) it reads as kinda generic (calling it apu), but then has some specifics around device binding.

Dave.